Solid-State NMR Spectroscopy: A Key Tool to Unravel the Supramolecular Structure of Drug Delivery Systems

Abstract

In the past decades, nanosized drug delivery systems (DDS) have been extensively developed and studied as a promising way to improve the performance of a drug and reduce its undesirable side effects. DDSs are usually very complex supramolecular assemblies made of a core that contains the active substance(s) and ensures a controlled release, which is surrounded by a corona that stabilizes the particles and ensures the delivery to the targeted cells. To optimize the design of engineered DDSs, it is essential to gain a comprehensive understanding of these core–shell assemblies at the atomic level. In this review, we illustrate how solid-state nuclear magnetic resonance (ssNMR) spectroscopy has become an essential tool in DDS design.

Degradation Mechanism of Metal–Organic Framework Drug Nanocarriers Studied by Solid-State Nuclear Magnetic Resonance and X-ray Absorption Near-Edge Structure Spectroscopy

“…43,44 For porous drug delivery systems, ssNMR spectroscopy has been mainly used to study mesoporous silica 45−47 and MOFs. 48,49 For MIL-100 (Fe), ssNMR spectroscopy gave indirect proof about the interaction between the strong paramagnetic Fe(III) and the drug azidothymidine triphosphate or the coating cyclodextrin phosphate (CD-P). 18,26 For diamagnetic MIL-100(Al), ssNMR spectroscopy provided insights about the host−guest interaction and location of the drugs adenosine triphosphate (ATP) and doxorubicin as well as the surface coating cyclodextrin-phosphate (CD-P).…”

“…Deviations from periodic structures in MOFs can happen after chemical modification or functionalization, which are often not detected by routine characterization techniques such as X-ray diffraction and infrared spectroscopy. In this case, ssNMR spectroscopy is a technique of choice for locally probing atoms, their neighboring environments, and chemical bonds while keeping the MOF intact. , It has been used extensively to determine the structure of new MOFs ,, and the adsorption–desorption mechanism of liquid and gases. , For porous drug delivery systems, ssNMR spectroscopy has been mainly used to study mesoporous silica − and MOFs. , For MIL-100­(Fe), ssNMR spectroscopy gave indirect proof about the interaction between the strong paramagnetic Fe­(III) and the drug azidothymidine triphosphate or the coating cyclodextrin phosphate (CD-P). , For diamagnetic MIL-100­(Al), ssNMR spectroscopy provided insights about the host–guest interaction and location of the drugs adenosine triphosphate (ATP) and doxorubicin as well as the surface coating cyclodextrin-phosphate (CD-P). , …”

“…It has been used extensively to determine the structure of new MOFs 7,41,42 , and the adsorption-desorption mechanism of liquid and gases 43,44 . For porous drug delivery systems, ssNMR spectroscopy has been mainly used to study mesoporous silica [45][46][47] and MOFs 48,49 . For MIL-100(Fe), ssNMR spectroscopy gave indirect proof about the interaction between the strong paramagnetic Fe(III) and the drug azidothymidine triphosphate or the coating cyclodextrin phosphate (CD-P) 18,26 .…”

Physicochemical Characterization of Nanobiocomposites

“…The energy is then emitted at the same frequency when the spin returns to its base level. Capturing these signals will give an NMR spectrum with characteristic chemical shifts for the spinning nucleus [32]. The precise resonant frequency of the energy transition is affected by electron shielding, which in turn is dependent on the chemical environment (i.e., the functional group within a polymer).…”

“…NMR can be used to characterize liquid NBCs samples like gels, dispersion, melt, and solutions with increased spectral specificity compared to solid samples [31,32]. Consequently, dilution, dispersion, increased temperature, etc., can give more information related to polymeric microstructure, its dynamics, and interactions with other ingredients within an NBC [33].…”